To cite package ‘selac’ in publications use:

  Beaulieu J, Chai J, Gilchrist M, Landerer C, Derryberry G, O'Meara B
  (2021). _selac: Selection Models for Amino Acid and/or Codon
  Evolution_. R package version 1.7.5,
  <https://github.com/bomeara/selac>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {selac: Selection Models for Amino Acid and/or Codon Evolution},
    author = {Jeremy Beaulieu and JJ Chai and Mike Gilchrist and Cedric Landerer and Graham Derryberry and Brian O'Meara},
    year = {2021},
    note = {R package version 1.7.5},
    url = {https://github.com/bomeara/selac},
  }